1. Technical Field
Various embodiments of the present invention relate generally to a semiconductor memory device and, more particularly, to a semiconductor memory device including memory cells stacked in a direction vertical to a substrate.
2. Related Art
One possible way to increase storage capacity is to provide a larger number of memory cells within a predetermined area. The number of memory cells may be increased by reducing memory cell size, but there are limitations in memory cell size reduction. A method for increasing the number of memory cells is to provide a three-dimensional (3D) structured memory block or memory string where memory cells are stacked in a direction vertical to a semiconductor substrate. The 3D structured memory string may include a vertical channel that is formed of silicon. The vertical channel may be formed between a bit line and a common source line.
Recently, a method of increasing density of three-dimensional memory blocks within a predetermined area has been in demand, and a method of preventing deterioration of electrical characteristics caused thereby has also been in demand.